Chemical reactor boiler assembly

ABSTRACT

A compact boiler unit of the type used for torpedo propulsion for transferring chemical reaction heat to a working medium. The reaction takes place in an annular zone defined between two concentric cylindrical wall elements and two annular end plate elements secured thereto, the cylindrical wall elements formed of continuous laterally bonded turns of a helical tubular conduit and the end plate elements provided with circumferentially spaced opposed reactant nozzle units for injecting reactant fluid into the annular zone to create maximum turbulent mixing therein. The working medium is moved in a helical path first through the inner helical conduit to generate vapor and then through the outer helical conduit to superheat the vapor. Centrifugal action during movement of the medium through the inner helical path breaks up and removes vapor bubbles to enhance heat transfer and reduce overheating which could cause conduit burnout. Maximum centrifugal force is advantageously developed along the outer surface of the inner conduit wall where best heat transfer potential and maximum burnout danger exist.

United States Patent 1191 Olson et al.

1 Aug. 21, 1973 CHEMICAL REACTOR BOILER ASSEMBLY [75] l'nventorszbonald ltfison; lit Elie] H. I

Kiely, both of State College, Pa.

[73] Assignee: The United States of America as represented by the Secretary of the Navy [22] Filed: June 22, 1972 [21] Appl. No.: 265,118

Primary Examiner-John .l. Camby Assistant Examiner-James C. Ye u n g Attorney-R. S. Sciascia and Henry Hansen ABSTRACT A compact boiler unit of the type used for torpedo propulsion for transferring chemical reaction heat to a working medium. The reaction takes place in an annular zone defined between two concentric cylindrical wall elements and two annular end plate elements se cured thereto, the cylindrical wall elements formed of continuous laterally bonded turns of a helical tubular conduit and the end plate elements provided with circumferentially spaced opposed reactant nozzle units for injecting reactant fluid into the annular zone to create maximum turbulent mixing therein. The working medium is moved in a helical path first through the inner helical conduit to generate vapor and then through the outer helical conduit to superheat the vapor. Centrifugal action during movement of the medium through the inner helical path breaks up and removes vapor bubbles to enhance heat transfer and reduce overheating which could cause conduit burnout. Maximum centrifugal force is advantageously developed along the outer surface of the inner conduit wall where best heat transfer potential and maximum burnout danger exist.

11 Claims, 4 Drawlng Flgures PATENTEDAUGZI ms 3; 753.423

SHEET 2 [IF 2 CHEMICAL REACTOR BOILER ASSEMBLY STATEMENT OF GOVERNMENT INTEREST The invention described herein may be manufactured and used by or for The Government of the United States of America for governmental purposes without the payment of any royalties thereon or therefor.

BACKGROUND OF THE INVENTION This invention relates generally to the field of heat transfer equipment for heating and vaporizing a liquid medium. More specifically the invention relates to an improved chemical reactor boiler of low cost, reduced size, and high efficiency especially adapted for torpedo propulsion where combustion products are not released from the system, and where all components must be run at maximum operating limits and conditions for efficiency and yet must function with a high degree of reliability. In addition, these requirements should be met at the lowest practicable cost. These operating and design requirements are quite difi'erent from those of ordinary industrial or commercial equipment.

Chemical reactor boilers have been used for torpedo propulsion but do not appear to have met these unusual requirements in that they are of complex expensive design and construction, and do not appear to have the low cost optimum combination of specific design features of the present invention which are adapted to perform most effectively where the maximum heat transfer potential exists, and provide most reliability and protection against failure where the greatest dangers, such as tube burnout, exist.

SUMMARY OF THE INVENTION The shortcomings and disadvantages of the prior art equipment have been overcome and the hereinaftermentioned objects of the invention have been achieved by an improved chemical reactor boiler assembly comprising in combination: a first hollow conduit element of given internal size and formed in an elongated tight helical coil configuration with adjacent turns of said helical coil configuration bonded together to form a first substantially cylindrical integral inner wall member of given diameter; a second hollow conduit element of relatively larger internal size formed in an elongated tight helical coil configuration with adjacent turns thereof bonded together to form a second substantially cylindrical integral outer wall member of a given diameter larger than the diameter of said first wall member, the axial dimension of said cylindrical wall members being substantially equal and said cylindrical wall members being maintained in coextensive concentric relationship by a first and a second annular end plate elements bonded to opposed axial end portions of the two cylindrical wall members to form a pressure-tight annular reaction zone between the two annular end plate elements and the inner and outer cylindrical wall members, one end of the first conduit element joined to and communicating with the corresponding end of the second conduit element, the other end of said first conduit element constructed and arranged to receive a vaporizable liquid medium at a given pressure and at a given rate of flow, and the other end of said second conduit element constructed and arranged to supply said medium as a superheated vapor under pressure for use in a heat engine; combustion means cooperating with said elements defining said annular reaction zone for initiating and maintaining an exothermic reaction of given heat output therein sufficient to vaporize the liquid medium supplied to said first conduit element and superheat the resulting vapor during a single pass through said first and second conduit elements, the given pressure, the given rate, the given diameters, and given internal sizes of said first and second conduit elements all predetermined and selected relative to each other and relative to the heat output of the exothermic reaction, such that maximum velocity and centrifugal forces are generated during movement of said liquid medium through said first conduit element sufficient to break up and remove vapor bubbles formed in said liquid medium along the outer surface of the inner helical coils of the first conduit element to enhance the heat transfer rate and reduce overheating of these portions of the conduit element where highest heat transfer potential and maximum danger of conduit burnout exist, and such that the vaporized medium is superheated as it passes through the second conduit element.

STATEMENT OF THE OBJECTS OF THE INVENTION It is an object of this invention to provide an improved chemical reactor boiler assembly for use in torpedo propulsion plants and other similar end use applications, an improved assembly with high efficiency and reliability which are provided in a simple, low cost design specifically tailored to give highest protection against failure where highest risk occurs in the system and to give highestefficiency where greatest potential for energy transfer exists.

Other objects, advantages, and novel features of the invention will appear from the following detailed description when considered in conjunction with the claims and accompanying drawings wherein:

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a partial longitudinal cross sectional view of an improved chemical reactor boiler assembly embodying features of the invention taken on line 1-1 of FIG.

FIG. 2 is a end view of the left end of the assembly shown in FIG. 1;

FIG. 3 is an enlarged partial longitudinal cross sectional view of one of the helical coils of the conduit forming the inner cylindrical wall of the reaction chamber of the boiler assembly of FIGS. 1 and 2 illustrating the centrifugal action of the liquid medium in the circular path to produce the desirable sweeping action to break up and remove vapor bubbles formed at the tube wall surface which is adjacent the inner portion of the boiler assembly reaction chamber and where the maximum potential for both heat transfer and tube burnout exist; and

FIG. 4 is a partial enlarged longitudinal cross sectional view of a reactant injection nozzle unit used to supply reactant material into the boiler assembly reaction chamber and showing the removable plug element in its initial position prior to commencement of the reaction in the reaction chamber.

DESCRIPTION OF THE PREFERRED EMBODIMENT The improved chemical reactor boiler assembly embodying features of this invention, as shown in FIGS. 1 and 2 of the drawing, consists of a first hollow conduit element of given internal size formed in an elongated tight helical coil configuration with adjacent turns IC of said helical coil configuration bonded together by suitable means such as welding or brazing to form a first substantially cylindrical integral pressure-tight inner wall member of a given diameter, and a second hollow conduit element of relatively larger internal size also formed in an elongated tight helical coil configuration with adjacent turns C thereof bonded together by suitable means as the first conduit element to form a second substantially cylindrical integral pressure-tight outer wall member of a diameter significantly larger than the diameter of said first wall member. The conduit elements are formed preferably of a metal with suitable strength and heat resistant properties such as steel. The cylindrical wall members are substantially equal in axial dimension and are maintained in coextensive coaxial relationship by two annular end plate elements Ell and EP2 which are bonded in pressuretight relationship to the axial end portions of the two cylindrical wall members by suitable means such as welding or brazing to form a pressure-tight annular reaction zone RC between the two annular end plate elements EPI and EPZ, and the turns IC and DC of the conduit elements forming the inner and outer cylindrical wall members as shown best in FIG. 1. The first conduit element IC forming the inner cylindrical wall member is connected at its right end, as viewed in FIG. 1, with and in communication with the right hand end of the second conduit element 0C.

The left hand end (FIG. 1) of the first conduit element IC is constructed and arranged to be connected to a source (not shown) of a vaporizable liquid medium at a given pressure and rate of flow. The left hand end of the second conduit OC (FIG. 1) is constructed and arranged to be connected to supply the medium as a superheated vapor to a suitable heat engine (not shown). A predetermined quantity of a suitable fuel such as one of the alkali metal fuels, comprising for example, lithium or sodium in solid or liquid form is initially stored in the reaction zone RC.

Each annular end plate element EPl and EPZ is provided with a plurality of circumferentially spaced oxidant injection nozzle units N for receiving a fluid oxidant such as sulfur hexafluoride from a pressurized source (not shown) and injecting it into the reaction zone RC as shown by the arrows in FIG. 1.

As best shown in FIG. 4 each nozzle unit N comprises a threaded plug element with a hexagonal bolt head portion and an internal passageway extending longitudinally therethrough. A hollow cylindrical heat shield element 1 l is secured by welding in an enlarged portion of this internal passageway. A main injection barrel element is secured in position in cylindrical heat shield element ll and in the passageway extending through the threaded plug element 10 as shown. The exterior of the main barrel element is provided with two radially enlarged portions 14 and 15 which define together with the body of the barrel element and the interior of heat shield element 11 a heat insulating chamber 13 to help protect the barrel element from the heat generated in the reaction zone RC into which it extends. The main barrel element is provided with a reduced portion 16 adapted to be connected to a pressurized oxidant source not shown, and an oxidant injection passageway 17A which communicates with an aligned injection passageway 17!! formed in an internal line sleeve 18 positioned inside the terminal portion of the main barrel element. Liner sleeve 18 is preferably formed of a material resistant to heat and chemical attack such as tungsten. A removable closure plug D formed of a suitable material such as polytetrafluroethylene, is releasably secured by frictional engagement at the terminal ends of the main barrel element and heat shield element 11 as shown to prevent entry of fuel material into the injection passageway when a small initiating charge (not shown) is rapidly burned or exploded in the reaction zone to start the chemical reaction. Application of the pressurized oxidizer fluid to the injection passageway 17A, 178, after the initiating charge has commenced the reaction, blows out and removes plug D so that supply of the oxidant can maintain the highly exothermic reaction by combining with the fuel in the reaction zone.

As shown in FIGS. 1 and 2 the injection nozzle units N are arranged and positioned in the end plate elements EP! and EPZ so that the streams of oxidant injected by one set of nozzle units impinge on the streams of oxidant injected from the other set of nozzle units to create a high degree of turbulent mixing for efficient reaction between the fuel and oxidant and to insure optimum heat transfer from the hot reaction materials to the conduit turns IC and OC forming the cylindrical v wall members of the reaction zone. This optimum heat transfer aspect permits a more rapid power level response to changes in the controlled oxidant flow rate. It is contemplated within the scope of the invention, that the injection nozzle units N may be oriented either opposed as illustrated, or staggered, even including angled positions, if desirable. Their orientation is selected to provide maximum turbulence, maximum mixing, and maximum heat transfer.

During the exothermic reaction in reaction zone RC a vaporizable medium such as water or mercury is supplied at a predetermined pressure and flow rate to inlet WI from which it passes through the turns lC of the first conduit element forming the cylindrical inner wall member. During passage of the medium through the first conduit element fonning the inner cylindrical wall member it boils or is vaporized by the heat transferred thereto from the reaction zone RC via the conduit element walls. After being vaporized and passing through the turns IC of the first inner cylindrical wall member, the medium moves radially outwardly at the right hand end of the assembly (FIG. 1) and enters the turns 00 of the second conduit element forming the second outer cylindrical wall member and moves in a helical path to the left where it exits as superheated vapor from outlet S0.

The turns lC of the first conduit element are sufficiently reduced in size internally and of a sufficient ra-n dius of curvature relativeto the pressure, velocity, and specific gravity of the liquid medium so that a centrifugal scrubbing action occurs taking advantage of the difference in specific gravity between the vapor and liquid, as shown in FIG. 3 to break up and remove vapor bubbles asthey form on the outer portions of conduit turns 1G to obtain maximum heat transfer at these portions and prevent tube burnout at these portions where, due to the construction of the assembly, maximum heat and temperatures also are developed by the reaction in the reaction zone. This is a highly advantageous feature and contributes significantly to the high efficieney and reliability of the improved assembly of the invention.

It is believed to be clear that an improved chemical reactor boiler has been providedin accordance with the objects of the invention.

What is claimed is: i

1. An improved chemical reactor boiler assembly comprising, in combination:

a first hollow conduit element of given internal size and formed in an elongated tight helical coil configuration with adjacent turns of said helical coil configuration bonded together to form a first substantially cylindrical integral inner wall member of given diameter;

a second hollow conduit element of relatively larger internal size formed in an elongated tight helical coil configuration with adjacent turns thereof bonded together to form a second substantially cylindrical integral outer wall member of a given diameter larger than the diameter of said first wall member, the axial dimension of said cylindrical wall members being substantially equal and saidcylindrical wall members being maintained in coextensive concentric relationship by a first and a second annular end plate elements bonded to opposed axial end portions of the two cylindrical wall members to form a pressure-tight annular reaction zone between the two annular endplate elements and the inner and outer cylindrical wall members, one end of the first conduit element joined to and communicating with the corresponding end of the second conduit element, the other end of said first conduit element constructed and arranged to receive a vaporizable liquid medium at a given pressure and at a given rate of flow, and the other end of said second conduit element constructed and arranged to supply said medium as a superheated,

vapor under pressure for use in a heat engine;

combustion means cooperating with said elements defining said annular reaction zone for initiating and maintaining an exothermic reaction of given heat output therein sufficient to vaporize the liquid medium supplied to said first conduit element and superheat the resulting vapor during a single pass through said first and second conduit elements, the given pressure, the given rate, the given diameters, and given internal sizes of said first and second conduit elements all predetermined and selected relative to each other and relative to the heat output of the exothermic reaction, such that maximum velocity and centrifugal forces are generated during movement of said liquid medium through said first conduit element sufficient to break up and remove vapor bubbles formed in said liquid medium along the inner portions of the helical coils of the first conduit element to enhance the heat transfer rate and reduce overheating of these portions of the conduit element where highest heat transfer potential and maximum danger of conduit burnout exist, and such that the vaporized medium is superheated as it passes through the second conduit element.

2. The improved assembly of claim 1 in which said combustion means comprises two opposing sets of reactant injection nozzle units circumferentially spaced around each of said annular end plate elements and ex tending inwardly into the annular reaction zone, each of said nozzle units constructed and arranged to receive a a hypergolic fluid reactant at an elevated pressure, said nozzle units further arranged and positioned such that streams of reactant injected by one set of nozzle units interact with the streams of reactant injected from the other set of nozzle units to create a high degree of turbulent mixing for efficient reactioh in the reaction zone.

3. The improved assemblyof claim 2 in which each nozzle unit comprises a main barrel element having a reactant injection passageway therethrough, a heat shield element surrounding said barrel element and defining a closed annular heat insulating chamber to protect the main barrel element from heat generated in the reaction zone, said nozzle unit further comprising a removable closure plug element releasably sealing the injection passageway by frictional engagement with said nozzle unit structure and removable by initial pressure applied internally to said injection passageway.

4. The improved assembly of claim 3 in which said reaction zone is constructed and arranged to contain a predetermined amount of a fuel reactant and said nozzle units are constructed and arranged to inject an oxidizing reactant. i V

5. The improved'assembly of claim 4 in which said annular reaction zone is completely enclosed by said defining elements except for communication with the reactant injection passageways of said nozzle units.

6. The improved assembly of claim 5 in which said main barrel elements is provided with an internal liner sleeve formed of tungsten.

7. An improved nozzle assembly in combination with an annular reaction chamber comprising:

two opposing sets of reactant injection nozzle units circumferentially spaced around said chamber, each unit constructed and arranged to receivea hypergolic fluid reactant at an elevated pressure, said unit further arranged and positioned such that streams of reactant injected by one set of nozzle units interact with the streams of reactant injected from the other set of nozzle units to create a high degree of turbulent mixing for efficient reaction in said chamber. p n

-8. The improved assembly of claim 7 in which each nozzle unit com-prises a main barrel element having a reactant injection passageway therethrough, a heat shield element surrounding said barrel element and defining a closed annular heat insulating chamber to protect the main barrel element from heat generated in the reaction zone, said nozzle unit further comprising a removable closure plug element releasably sealing the injection passageway by frictional engagement with said nozzle unit structure and removable by initial pressure applied internally to said injection passageway.

9. The improved assembly of claim 8 in which said reaction chamber is constructed and arranged to contain a predetermined amount of a fuel reactant and said nozzle units are constructed and arranged to inject an oxidizing reactant.

10. The improved assembly of claim 9 in which said annular reaction chamber is completely enclosed by said defining elements except for communication with the reactant injection passageways of said nozzle units.

11. The improved assembly of claim 10 in which said main barrel element is provided with an internal liner sleeve formed of tunsten.

i i l i i 

1. An improved chemical reactor boiler assembly comprising, in combination: a first hollow conduit element of given internal size and formed in an elongated tight helical coil configuration with adjacent turns of said helical coil configuration bonded together to form a first substantially cylindrical integral inner wall member of given diameter; a second hollow conduit element of relatively larger internal size formed in an elongated tight helical coil configuration with adjacent turns thereof bonded together to form a second substantially cylindrical integral outer wall member of a given diameter Larger than the diameter of said first wall member, the axial dimension of said cylindrical wall members being substantially equal and said cylindrical wall members being maintained in coextensive concentric relationship by a first and a second annular end plate elements bonded to opposed axial end portions of the two cylindrical wall members to form a pressure-tight annular reaction zone between the two annular end plate elements and the inner and outer cylindrical wall members, one end of the first conduit element joined to and communicating with the corresponding end of the second conduit element, the other end of said first conduit element constructed and arranged to receive a vaporizable liquid medium at a given pressure and at a given rate of flow, and the other end of said second conduit element constructed and arranged to supply said medium as a superheated vapor under pressure for use in a heat engine; combustion means cooperating with said elements defining said annular reaction zone for initiating and maintaining an exothermic reaction of given heat output therein sufficient to vaporize the liquid medium supplied to said first conduit element and superheat the resulting vapor during a single pass through said first and second conduit elements, the given pressure, the given rate, the given diameters, and given internal sizes of said first and second conduit elements all predetermined and selected relative to each other and relative to the heat output of the exothermic reaction, such that maximum velocity and centrifugal forces are generated during movement of said liquid medium through said first conduit element sufficient to break up and remove vapor bubbles formed in said liquid medium along the inner portions of the helical coils of the first conduit element to enhance the heat transfer rate and reduce overheating of these portions of the conduit element where highest heat transfer potential and maximum danger of conduit burnout exist, and such that the vaporized medium is superheated as it passes through the second conduit element.
 2. The improved assembly of claim 1 in which said combustion means comprises two opposing sets of reactant injection nozzle units circumferentially spaced around each of said annular end plate elements and extending inwardly into the annular reaction zone, each of said nozzle units constructed and arranged to receive a hypergolic fluid reactant at an elevated pressure, said nozzle units further arranged and positioned such that streams of reactant injected by one set of nozzle units interact with the streams of reactant injected from the other set of nozzle units to create a high degree of turbulent mixing for efficient reaction in the reaction zone.
 3. The improved assembly of claim 2 in which each nozzle unit comprises a main barrel element having a reactant injection passageway therethrough, a heat shield element surrounding said barrel element and defining a closed annular heat insulating chamber to protect the main barrel element from heat generated in the reaction zone, said nozzle unit further comprising a removable closure plug element releasably sealing the injection passageway by frictional engagement with said nozzle unit structure and removable by initial pressure applied internally to said injection passageway.
 4. The improved assembly of claim 3 in which said reaction zone is constructed and arranged to contain a predetermined amount of a fuel reactant and said nozzle units are constructed and arranged to inject an oxidizing reactant.
 5. The improved assembly of claim 4 in which said annular reaction zone is completely enclosed by said defining elements except for communication with the reactant injection passageways of said nozzle units.
 6. The improved assembly of claim 5 in which said main barrel elements is provided with an internal liner sleeve formed of tungsten.
 7. An improved nozzle assembly in combination with an annular reaction chamber comprising: two opposing sets of reactant injeCtion nozzle units circumferentially spaced around said chamber, each unit constructed and arranged to receive a hypergolic fluid reactant at an elevated pressure, said unit further arranged and positioned such that streams of reactant injected by one set of nozzle units interact with the streams of reactant injected from the other set of nozzle units to create a high degree of turbulent mixing for efficient reaction in said chamber.
 8. The improved assembly of claim 7 in which each nozzle unit com-prises a main barrel element having a reactant injection passageway therethrough, a heat shield element surrounding said barrel element and defining a closed annular heat insulating chamber to protect the main barrel element from heat generated in the reaction zone, said nozzle unit further comprising a removable closure plug element releasably sealing the injection passageway by frictional engagement with said nozzle unit structure and removable by initial pressure applied internally to said injection passageway.
 9. The improved assembly of claim 8 in which said reaction chamber is constructed and arranged to contain a predetermined amount of a fuel reactant and said nozzle units are constructed and arranged to inject an oxidizing reactant.
 10. The improved assembly of claim 9 in which said annular reaction chamber is completely enclosed by said defining elements except for communication with the reactant injection passageways of said nozzle units.
 11. The improved assembly of claim 10 in which said main barrel element is provided with an internal liner sleeve formed of tunsten. 